In July 2010, Foursquare had 2 million users performing 1 million check-ins per day. By the end of the year, that number had risen to 5 million users performing 2 million check-ins per day. Impressive growth, yet this means check-ins per user declined from 0.5 per person to 0.4. It also suggests that many of those five million users aren't active.

The trend for Facebook Places is even worse. Facebook had at least 30 million members check in at least once in a shorter time frame as a newer service with a larger built in user base. Yet Facebook Places offers even less value than a Foursquare check-in. There are no points to win and no discovery element like tips; it's just a flat statement that, "I am at Starbucks." As a result, early indications are that Facebook check-ins strongly lag Foursquare check-ins.

Only 30 million people have used Facebook Places, one report finds. If that sounds impressive, consider that it represents just 6 percent of Facebook users. And that’s not the number who use it. That’s the number who have tried it.

First of all, you or a Facebook friend in your group will need a smartphone. If you don't have an iPhone, you'll have to use the Facebook touch mobile site on a browser that supports both HTML 5 and geolocation.

The company does plan to roll out Android and BlackBerry versions of Places, but they haven't released any specific dates for those releases yet.

To use Places, go to the Places tab on the iPhone application or touch.facebook.com. You'll first be asked if Facebook is allowed to know your location. Once you click "allow," you'll enter the Places interface. From there, you can share your location with friends, find out where your friends are (if they're using Places), and discover new places near you.

You can add places, check in to places that already exist, and tag people who are with you. If you're checking in for a group, make sure you tag your friends before you checkin, yourself. For example, I added my house and checked in there. I then opened the Places page for a nearby sushi restaurant, tagged my boyfriend, and checked us both in there.